onsemi MJE3055T

Overview

MJE3055T from onsemi is an NPN silicon power transistor in a TO-220 package, rated for 60 V_CEO, 10 A_C, and 75 W dissipation at T_C = 25 °C, with h_FE ≥ 20 at I_C = 4 A and V_CE = 4 V - used in linear power amplifiers, DC motor drivers, and switching regulators.

For engineers reviewing the MJE3055T datasheet, pinout, applications, or equivalent options, key selection considerations include safe operating area (SOA) limits at elevated case temperatures, V_CE(sat) ≤ 1.1 V at I_C/I_B = 10, thermal resistance R_θJC = 1.67 °C/W, and Pb-free RoHS-compliant packaging.

Technical Context

The MJE3055T operates as a medium-power bipolar junction transistor optimized for linear and switching operation up to 2 MHz f_T, with complementary PNP pairing via MJE2955T. Its SOA is constrained by second breakdown and thermal limits, requiring heatsinking above ~25 °C ambient.

It features low V_BE(on) ≤ 1.8 V at I_C = 4 A and exhibits I_CEO ≤ 700 µA at V_CE = 30 V, supporting stable biasing in Class AB amplifier stages and robust current control in relay/actuator driver circuits.

Key Specifications

Pinout & Package

Package: TO-220 (Case 221A-09, Style 1), 3-pin plastic power package with metal tab electrically connected to collector (pins 2 and 4). Mounting hole enables mechanical attachment to heatsink.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN power transistor applications.

Compared with TIP3055 and 2N3055, the MJE3055T offers identical voltage/current ratings to TIP3055 but in a more compact TO-220 form factor, while providing higher minimum h_FE than 2N3055 - making it optimal for space-constrained, gain-sensitive linear amplifier and motor drive designs.

Availability

MJE3055T is available at Aetrix Electronics and suitable for audio power amplifiers, DC motor drivers, and linear voltage regulators requiring stable component supply and RoHS-compliant manufacturing.

Supply support for MJE3055T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

onsemi is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The MJE3055T belongs to onsemi's complementary silicon power transistor family, designed specifically for cost-effective, high-reliability linear amplification and medium-duty switching in consumer and industrial equipment.

FAQ

What is the maximum safe operating case temperature for the MJE3055T?

The MJE3055T has a maximum operating junction temperature of +150 °C and a thermal resistance R_θJC of 1.67 °C/W. To maintain T_J ≤ 150 °C at 75 W dissipation, T_C must remain ≤ 25 °C - meaning active heatsinking is required above ~25 °C ambient. Derating begins at 0.6 W/°C above 25 °C, limiting usable power to ~45 W at T_C = 100 °C. The MJE3055T datasheet Figure 3 confirms this linear derating behavior.

Is the MJE3055T pin-compatible with the MJE2955T?

No - the MJE3055T (NPN) and MJE2955T (PNP) share identical TO-220 package dimensions and pinout (Style 1: Pin 1 = Base, Pins 2 & 4 = Collector, Pin 3 = Emitter), but they are complementary devices, not pin-compatible replacements. Both require matching base-drive polarity and bias networks. The MJE3055T cannot substitute for the MJE2955T without circuit redesign due to opposite polarity and differing V_EB and h_FE characteristics.

Does the MJE3055T require a heatsink in all applications?

Yes - the MJE3055T must be mounted to a heatsink in any application where power dissipation exceeds ~5 W continuously. With R_θJC = 1.67 °C/W and T_J(max) = 150 °C, even modest dissipation (e.g., 20 W at T_C = 60 °C) raises junction temperature beyond safe limits without thermal management. The MJE3055T Safe Operating Area curves (Figure 1) assume proper heatsinking; operation without one risks second breakdown or thermal runaway.

What is the typical V_BE(on) of the MJE3055T at rated current?

The MJE3055T exhibits V_BE(on) ≤ 1.8 V at I_C = 4 A and V_CE = 4 V, per the Electrical Characteristics table. This value reflects forward-biased base-emitter junction voltage under hard saturation conditions. At lower currents (e.g., I_C = 1 A), V_BE drops to ~1.3 V. Designers should use this 1.8 V figure when calculating base resistor values for full conduction, as confirmed in the MJE3055T datasheet Figure 4.

Can the MJE3055T be used in switching power supplies?

Yes - the MJE3055T supports switching operation up to ~20 kHz in hard-switched topologies and higher frequencies in resonant or soft-switched designs, thanks to its f_T = 2.0 MHz and V_CE(sat) ≤ 1.1 V. However, its relatively high storage time (not specified in the datasheet) and lack of optimized switching parameters mean it is best suited for low-to-medium frequency (<100 kHz) applications like offline SMPS standby supplies or DC-DC converters with moderate efficiency targets. The MJE3055T is not recommended for high-frequency (>500 kHz) or zero-voltage-switching designs.